What makes up talc

Researchers might also expose normal cells in a lab dish to the substance to see if it causes the types of changes that are seen in cancer cells. Studies in people: Another type of study looks at cancer risks among different groups of people. Such a study might compare the cancer risk in a group exposed to a substance to the risk in a group not exposed to it, or compare it to what would be expected in the general population.

But sometimes it can be hard to know what the results of these studies mean, because many other factors might affect the results. In most cases neither type of study provides enough evidence on its own, so researchers usually look at both lab-based and human studies when trying to figure out if something causes cancer.

Studies that exposed lab animals rats, mice, and hamsters to asbestos-free talc in various ways have had mixed results, with some showing tumor formation and others not finding any. It has been suggested that talcum powder might cause cancer in the ovaries if the powder particles applied to the genital area or on sanitary napkins, diaphragms, or condoms were to travel through the vagina, uterus, and fallopian tubes to the ovary.

Many studies in women have looked at the possible link between talcum powder and cancer of the ovary. Findings have been mixed, with some studies reporting a slightly increased risk and some reporting no increase.

Because of this, even the largest studies done so far might not have been big enough to detect a very small increase in risk, if it exists. These are only a few of the ways in which this highly versatile ingredient is used in cosmetics. The same material is also described as Pharmaceutical grade talc and is used in both medicines in tablets and in foods such as chewing gum.

Over the years, the safety of talc has sometimes been questioned through reports in the media. One of the most common claims is that talc use increases the risk of ovarian cancer, this in spite of no causal link between cosmetic talc and cancer ever having being shown.

Even so, a number of stories can be found circulating the internet making similar, unjustified claims that are not supported by the existing body of scientific evidence. During this workshop, participants agreed that there was no evidence to conclude that talc is capable of reaching the ovaries. In , the Expert Panel of the US Cosmetics Ingredient Review review of talc safety [1] again agreed that there is no known physiological mechanism by which talc can plausibly migrate from the perineum to the ovaries.

In the past, some researchers have claimed to have found particles of talc in surgically removed ovarian cancer tissue. However, finding particles believed to be talc in the tissues of patients must be interpreted with caution.

There is every chance that particles, which may or may not be talc, can be found in healthy samples too. Careful investigations in the past have shown that such particles are present everywhere in the environment, even in hospital operating theatres, and may even be in the substances used to prepare the tissue samples for analysis. Sometimes negative attention is given to cosmetic talc because of confusion over the difference between talc and asbestos. It is true that they are both hydrated magnesium silicates, but diamonds and barbeque charcoal briquettes are both made of carbon and no-one would think they were the same!

One vitally important difference between talc and asbestos is in their crystal structure. While talc is made up of tiny flat plates, asbestos is formed as thin fibres.

It is the specific fibrous structure of asbestos which contributes to its potentially harmful effects. Talc particles do not share this characteristic. It is sometimes rumoured that cosmetic talc is contaminated with asbestos fibres.

This is simply not the case. Some low-grade industrial talcs may contain many impurities including asbestos fibres but these grades of talc are not permitted for use in cosmetics. Only asbestos-free cosmetic grade talc of the highest quality and purity is used in cosmetics. Selective mining, testing and the application of rigorous quality standards ensure cosmetic talc is free of asbestos fibres.

Cosmetic manufacturers only source talc from reputable suppliers with strict testing controls. In , a US Government funded study, published in the Journal of the American Medical Association JAMA on a quarter of a million women and thought to be the largest of its kind on this topic, has found no link between talc and ovarian cancer.

The intention was to review all the available data on talc safety. After a two day hearing, the conclusion was that no hazards to health had been demonstrated in connection with the normal use of cosmetic talc. In , following a Petition by the US Cancer Prevention Coalition CDC seeking warning labelling on cosmetic talc products, the FDA performed a review of the safety of cosmetic talc, using all the relevant scientific literature, and found no evidence of a causal association between talc use in the perineal area and ovarian cancer.

The purpose was to review the human epidemiology studies investigating both the personal use of talc and exposure to talc in the workplace. In October , the NTP ruled that existing scientific data were insufficient to identify talc as a cancer causing agent and talc was withdrawn from its review process. It concluded that talc is safe for use in cosmetics in the present practices of use. It was concluded that there is limited evidence in humans for the carcinogenicity of perineal use of talc-based body powder, i.

As a result, application of talc in the genital area was classified as Group 2B; possibly carcinogenic to humans. The category 2B as used by IARC does not mean that talc is classed as carcinogenic, rather IARC takes a view that in the absence of all data, they place a cautious classification.

In fact one of the main IARC Committee members has recently co-authored a scientific paper taking into account the newer data available since the IARC review and commented "In summary perineal powder use did not appear to be associated with ovarian cancer risk in this large sample of postmenopausal women, even with use for long durations" [3]. Since the IARC review there have been studies published on large populations of women that clearly show that talc was not a carcinogen to the ovary.

These are noted below [2] [3]. Many scientific research papers and epidemiology studies have been published since the early s either supporting or opposing links between talc and ovarian cancer. Despite this, no scientific study has ever shown that talc causes ovarian cancer.

There are two types of epidemiology studies - 'retrospective' and 'prospective'. The vast majority of epidemiology studies that have investigated talc cancer risk are what scientists call 'retrospective studies' which look at how people's behaviour relates to disease. This requires the subjects to remember what they did in the past, as much as 20 or more years ago, and are likely to result in what statisticians describe as 'recall bias'.

In any epidemiology study it is vital to have a test and a control group that are exactly matched to make sure any 'confounding factors' are addressed, such as lifestyle choices and biased recall of personal habits over a period of time.

However the published retrospective studies on talc and ovarian cancer have been criticised in that they were not matched with controls. In more recent years there have been a number of 'prospective studies' which start at the beginning of the evaluation period and obtain all the required information at the beginning of a long term follow up.

Since the population groups of test and controls can be personally interviewed at the start of a study that will last for many years, any 'confounding factors' can be reduced or eliminated, meaning the studies are much more statistically robust.

There have been two large prospective studies on talc and ovarian cancer. The first was called the Nurses Health Study [2] published in and the second the Women's Health Study [3] published in Both looked at a many thousands of women over many years.

These show no causal relationship between talc use and ovarian cancer. We can rely on these studies because they don't suffer from the major problems of recall bias and poor controls - essentially the results of these prospective studies supersede the previous retrospective studies.

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Oral health problems. Likewise, the FDA would propose any related regulations through a public notice and comment process. Warning to Consumers. On October 18, , the FDA updated a Safety Alert and issued a Constituent Update warning consumers not to use certain cosmetic products tested positive for asbestos. On November 28, , the FDA and other government agency representatives attended a scientific and technical symposium designed to provide a forum for scientists to share their knowledge and experience in testing methods for analysis of talc, developing criteria used for fiber identification, and interpreting data.

For the full transcripts from the symposium, see:. The purpose of this government work group is to develop recommendations on topics related to testing methodologies, terminology, and criteria for data interpretation that can be applied to characterize mineral fibers present as contaminants in consumer products.

FDA's Talc Survey of The survey found no asbestos fibers or structures in any of the samples of cosmetic-grade raw material talc or cosmetic products containing talc. The results were limited, however, by the fact that only four of nine talc suppliers submitted samples and by the number of products tested. Tectonic movements always play a major role: earth movements allow the hydrothermal fluid to penetrate the mother-rock, generating permeability that makes reactions inside the rock mass possible.

The type of mineralisation depends essentially on the nature of the parent rock. Talc deposits are classified according to the parent rock from which they derive. There are four types of talc deposits:. This wide diversity of origin and types naturally gives rise to a wide variety of ores and product grades, which differ according to their mineralogical composition, colour and crystalline structure micro-crystalline or lamellar.

The main surfaces, known as basal surfaces, of the elementary sheet contain neither hydroxyl groups nor active ions, making talc both hydrophobic and inert. The size of an individual talc platelet i. It is this individual platelet size that determines a talc's lamellarity. A highly lamellar talc will have large individual platelets whereas a microcrystalline talc will have small platelets. The elementary sheets are stacked on top of one another, like flaky pastry, and because the binding forces known as Van de Waal's forces linking one elementary sheet to its neighbours are very weak, the platelets slide apart at the slightest touch, giving talc its characteristic softness.

Talc is odourless. It is insoluble in water and in weak acids and alkalis. Although talc has a marked affinity for certain organic chemicals, it generally has very little chemical reactivity. It is neither explosive nor flammable. Talcs differ according to their mineralogical composition, i. The most common mineral found with talc is chlorite, which is structurally and chemically very similar. Dolomite and magnesite are also often present. As we have seen above, talcs also differ in their degree of lamellarity.

Talc shows an affinity for certain organic chemicals. It is therefore organophilic. In the case of talc's affinity for polypropylene, a likely explanation is that the position of the oxygen atoms on the surface of the talc platelet corresponds to the carbon bonds on the surface of the polypropylene crystal. Talc's organophilic properties are used to great benefit in a number of applications, for instance, it helps polypropylene to crystallise.

In papermaking, the talc particles attract the undesirable resin droplets, i. This is known as pitch control.